/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.reactive.function.client;

import java.nio.charset.StandardCharsets;
import java.util.function.Consumer;

import reactor.core.publisher.Flux;

import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseCookie;
import org.springframework.http.client.reactive.ClientHttpResponse;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;

/**
 * Default implementation of {@link ClientResponse.Builder}.
 *
 * @author Arjen Poutsma
 * @since 5.0.5
 */
final class DefaultClientResponseBuilder implements ClientResponse.Builder {

    private ExchangeStrategies strategies;

    private HttpStatus statusCode = HttpStatus.OK;

    private final HttpHeaders headers = new HttpHeaders();

    private final MultiValueMap<String, ResponseCookie> cookies = new LinkedMultiValueMap<>();

    private Flux<DataBuffer> body = Flux.empty();


    public DefaultClientResponseBuilder(ExchangeStrategies strategies) {
        Assert.notNull(strategies, "ExchangeStrategies must not be null");
        this.strategies = strategies;
    }

    public DefaultClientResponseBuilder(ClientResponse other) {
        Assert.notNull(other, "ClientResponse must not be null");
        this.strategies = other.strategies();
        statusCode(other.statusCode());
        headers(headers -> headers.addAll(other.headers().asHttpHeaders()));
        cookies(cookies -> cookies.addAll(other.cookies()));
    }


    @Override
    public DefaultClientResponseBuilder statusCode(HttpStatus statusCode) {
        Assert.notNull(statusCode, "HttpStatus must not be null");
        this.statusCode = statusCode;
        return this;
    }

    @Override
    public ClientResponse.Builder header(String headerName, String... headerValues) {
        for (String headerValue : headerValues) {
            this.headers.add(headerName, headerValue);
        }
        return this;
    }

    @Override
    public ClientResponse.Builder headers(Consumer<HttpHeaders> headersConsumer) {
        headersConsumer.accept(this.headers);
        return this;
    }

    @Override
    public DefaultClientResponseBuilder cookie(String name, String... values) {
        for (String value : values) {
            this.cookies.add(name, ResponseCookie.from(name, value).build());
        }
        return this;
    }

    @Override
    public ClientResponse.Builder cookies(Consumer<MultiValueMap<String, ResponseCookie>> cookiesConsumer) {
        cookiesConsumer.accept(this.cookies);
        return this;
    }

    @Override
    public ClientResponse.Builder body(Flux<DataBuffer> body) {
        Assert.notNull(body, "Body must not be null");
        releaseBody();
        this.body = body;
        return this;
    }

    @Override
    public ClientResponse.Builder body(String body) {
        Assert.notNull(body, "Body must not be null");
        releaseBody();
        DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();
        this.body = Flux.just(body).
                map(s -> {
                    byte[] bytes = body.getBytes(StandardCharsets.UTF_8);
                    return dataBufferFactory.wrap(bytes);
                });
        return this;
    }

    private void releaseBody() {
        this.body.subscribe(DataBufferUtils.releaseConsumer());
    }

    @Override
    public ClientResponse build() {

        ClientHttpResponse httpResponse =
                new BuiltClientHttpResponse(this.statusCode, this.headers, this.cookies, this.body);

        // When building ClientResponse manually, the ClientRequest.logPrefix() has to be passed,
        // e.g. via ClientResponse.Builder, but this (builder) is not used currently.

        return new DefaultClientResponse(httpResponse, this.strategies, "");
    }


    private static class BuiltClientHttpResponse implements ClientHttpResponse {

        private final HttpStatus statusCode;

        private final HttpHeaders headers;

        private final MultiValueMap<String, ResponseCookie> cookies;

        private final Flux<DataBuffer> body;

        public BuiltClientHttpResponse(HttpStatus statusCode, HttpHeaders headers,
                                       MultiValueMap<String, ResponseCookie> cookies, Flux<DataBuffer> body) {

            this.statusCode = statusCode;
            this.headers = HttpHeaders.readOnlyHttpHeaders(headers);
            this.cookies = CollectionUtils.unmodifiableMultiValueMap(cookies);
            this.body = body;
        }

        @Override
        public HttpStatus getStatusCode() {
            return this.statusCode;
        }

        @Override
        public int getRawStatusCode() {
            return this.statusCode.value();
        }

        @Override
        public HttpHeaders getHeaders() {
            return this.headers;
        }

        @Override
        public MultiValueMap<String, ResponseCookie> getCookies() {
            return this.cookies;
        }

        @Override
        public Flux<DataBuffer> getBody() {
            return this.body;
        }
    }

}
